1. Field of the Invention
The invention relates to a fabricating method of a device and a forming method of a film. More particularly, the invention relates to a fabricating method of a light emitting device and a forming method of an organic layer.
2. Description of Related Art
An electroluminescent device is a semiconductor device capable of efficiently converting electrical energy into optical energy, and the organic electroluminescent device often serves as a light emitting device of indicator light, a display panel, and an optical pickup head. Since an organic electroluminescent device is characterized by the absence of viewing-angle dependence, simple manufacturing process, low costs, high response speed, wide operating temperature range, and full-color display, the organic electroluminescent device satisfies the requirement for the multi-media display and is likely to become a mainstream of the next generation flat panel display.
The organic electroluminescent device includes an anode, an organic light emitting layer, and a cathode. In order for the organic electroluminescent device to emit light, holes and electrons are injected into the organic light emitting layer respectively through the anode and the cathode. The electrons and the holes are re-combined in the organic light emitting layer to form photons, such that light is emitted. To enhance the light emitting efficiency of the organic electroluminescent device, a hole injection layer and a hole transporting layer are often configured between the anode and the organic light emitting layer, and an electron injection layer and an electron transporting layer are often configured between the cathode and the organic light emitting layer. Namely, there can be a plurality of organic functional layers between the anode and the cathode, and the organic functional layers may be a hole injection layer, a hole transporting layer, an organic light emitting layer, an electron injection layer, and an electron transporting layer sequentially stacked on the anode.
The organic functional layers are often formed by performing an evaporation process with use of a mask, which is however not cost-effective and is rather inapplicable to mass production. Hence, other techniques, e.g., a printing process, are proposed to replace the mask-using evaporation process. In the printing process, an organic material is dissolved into a volatile solvent to form a solution, and the solution containing the organic material is coated onto the substrate. After that, the solvent is evaporated to form the organic functional layer containing the organic material. Nonetheless, the organic functional layers are stacked and in contact with one another; therefore, the solvent for subsequently forming the organic functional layers may be in contact with the organic functional layers that are already formed, and the formed organic functional layers may be dissolved into the solvent, which further poses an impact on the device properties of the organic electroluminescent device. Since the organic functional layers have various types of materials, fabrication of the organic functional layers becomes much more difficult and complicated.